Quantification of Microcystin-degrading Bacteria in a Biofilm from a Practical Biological Treatment Facility by Real-time PCR

Abstract

A rapid decrease in the concentration of microcystin due to the decline of Microcystis spp. cells has been observed during fall in Japan. Past researches have shown the involvement of microcystin-degrading bacteria in this phenomenon, but the process by which it occurs has not yet been elucidated. In this research, microcystin-degrading bacteria were quantified using real-time TaqMan polymerase chain reaction. The new TaqMan probe was based on the sequence of the mlrA gene that is conserved in microcystin-degrading bacteria; new primers were similarly developed. These new primers and probe enabled the precise examination of microcystin-degrading bacteria in a biofilm. Moreover, the bacteria present in a biofilm from a practical biological treatment facility could be detected and quantified. The results showed that microcystin-degrading bacteria existed in the biofilm throughout the year, and the number of bacterial cells increased in fall.